Scorpion Venom Takes On Tumors

A Protein From The Poison Helps Deliver Radioactive Molecules To Cancer Cells.

March 3, 2005|By Robyn Shelton, Sentinel Medical Writer

After traditional medicine failed him, Pat Brenner turned to the dangerous sting of a scorpion to slow a growing brain tumor.

During treatments at an Orlando cancer hospital, the Port Orange man's brain has been injected twice with an experimental treatment based on a protein found in the venom of the giant yellow Israeli scorpion.

The protein is mixed with radioactive molecules, creating what doctors say is a highly targeted attack system for brain tumors. The scorpion protein seeks out malignant brain cells. The radioactive substance rides piggyback on the protein, delivering a tiny -- yet lethal -- dose of radiation to the cancerous tissue. Nearby healthy cells are spared.

At least, that's the theory being tested in an early study at the Florida Hospital Cancer Institute.

Brenner, 45, is the hospital's first patient to undergo the treatments. He has one more injection left in a series of three shots. Other patients will get up to six injections as doctors test varying doses. Additional studies are needed, but Brenner is hopeful.

"I know it sounds strange," said Brenner, a former auto mechanic who became ill in 2003. "Maybe it is a little out there, but you know, if it works, it's worth it."

The treatment is being developed by TransMolecular Inc., a biopharmaceutical company based in Birmingham, Ala.

In an earlier study involving just 18 patients, the company saw promising results, said Matthew A. Gonda, TransMolecular's chief executive officer. All the people in the study were in the worst-case scenario for brain cancer, with tumors that had grown back after having been removed by surgery.

Patients with these recurring tumors typically live only four to six months, but those in the study survived for an average of 6.3 months. Five of the 18 patients lived longer than a year, and two have survived more than two years after getting the treatment.

The study was too small to draw any conclusions about the therapy's effectiveness. Nevertheless, Gonda said one important thing to note is that the 18 patients received a single, small dose of the scorpion-based treatment.

"We anticipate we'll be able to amplify the effect with higher doses," Gonda said, adding that patients did not report side effects from the treatment.

Most cancer therapies, such as radiation and chemotherapy, can cause very debilitating side effects. Gonda said the venom treatment avoids the nausea, fatigue and other problems by targeting cancer cells with greater precision.

"You don't have to get sicker before you can get better," he said. "I think that's the unique thing about it because quality of life is very important to these patients."

The current study will involve about eight sites in the United States and Canada. It will be many months before its findings are known.

At Florida Hospital, about 20 patients will be enrolled in the testing, said Dr. Nicholas Avgeropoulos, co-medical director of the Neuro-Oncology Center at the hospital's cancer institute. The participants must have operable brain tumors that are primary malignancies, meaning the cancer did not start somewhere else and spread to the brain.

Avgeropoulos said the treatment is injected into the tumor site through a tiny tube -- or portal -- that has been implanted in the brain during surgery. The tube is underneath the scalp and not visible to others.

It helps deliver the scorpion protein and radioactive molecules to the target zone. The protein used is a purified, laboratory-made version of the one that occurs naturally in the giant yellow Israeli scorpion.

There are more than 1,300 species of scorpions on the planet and, despite their deadly reputation, very few are actually lethal to humans. The Israeli scorpion, which can grow to be about 8 inches long, cannot kill people.

The protein it carries, however, is highly attracted to another protein found on cancerous brain cells. This is why researchers decided to use the scorpion venom as the vehicle for delivering a dose of radiation. Avgeropoulos likens the therapy to a "smart missile" that homes in on cancerous cells with great accuracy.

If it works, Avgeropoulos said, the treatment could provide an alternative for people who have very few options.

"If patients have a recurrence or progression [of the brain tumor], we're in a really dire situation because the tumors are usually relentless and progress in a very debilitating fashion," he said. "The stakes are very high."

According to the American Cancer Society, an estimated 18,000 people will be diagnosed with malignant brain tumors in the United States this year.

Doctors continually are searching for better ways to stop their cancers.

Dr. George Bobustuc, who treats brain and spinal-cord tumors at M.D. Anderson Cancer Center Orlando, said he is skeptical about the scorpion-based therapy.

However, he added, some researchers have had promising results when using different proteins as a way to target cancer cells in other parts of the body.